What keys do i use to solve problems with variables in them on my fx-115 ES calculator

Sorry, It is not possible to solve equations on the Casio FX-82 ms. Try the Casio FX-115 ES/ FX-115 ES Plus, FX-991ES/ FX-881 ES Plus C.

What you want to do is solve the linear equation 2x=10 to find the value of the unknown x that makes the equality true. Solving an equation usually involves rearranging therms, factors and so on. However your calculator was not designed to handle the solution of equations, no matter how simple they are.
Some Casio scientific calculators can solve some types of equations (polynomials of degree 2 or 3, simultaneous linear equations in up to 3 unknowns). These are the FX-115 ES (Plus) and FX-991 ES (Plus C). Other equivalent models are sold in the world under different names.

The Casios FX-115 ES , FX-115 ES PLus, FX-991 ES, FX-991 ES Plus C can perfom numerical differentiation at a point, and numerical integration between two given limits.

Sorry, the Fx-115W is unable to solve equations of any type. In addition to that, the more sophisticated Casios such as the FX-991 ES solve linear equations of no more than 3 variables.

The FX-901 calculator seems to be the equivalent of the FX 260 Solar sold in North America. It does fraction calculations, permutation, statistics but lack the Equation Solver.
You cannot use it to solve equations.
Casio Scientific calculators that can handle equation solving are the FX-115 and FX-991.
Simplify your first equation by dividing all its terms by 3, then use elimination to carry out the solution by hand.

You don't need to calculate it. Just press
3 . 0 0 9 x10^x (-) 6
to enter the value.

x10^x is on the bottom row, to the right of the decimal point key.
(-) is on the far left column, above the RCL key.

It's just above the ENG key, to the left of the hyp key, on the second column from the left.

Hello,

Use your internet seach engine or go to the casio worldwide web site. A google search returned this link to the New-Zealand site.

http://casionz.co.nz/Site/Pronto/Files/user_manuals/FX-115ES%20991ES.PDF

Hope it helps

its the second key above the number 7 and it has the red A right above it

(x + 1) = 7