So, the problem is asking for one of the equations to be rewritten. Lets rewrite the second one. The way to create a system of equations that will cancel is to create a situation where the a or b of both equations add to 0. In this case, we can multiply the second equation by 3 to turn the 3y into 9y.
Our new system is and
. We can now add these together.
Adding each part straight down, we get the equation:
We now have an equation with a single variable, which also tells us that x is equal to 27.
Extra: To find the value of y after this, we merely need to plug in the value of x to one of the equations and solve for y.