00:01
This problem says for the given system of equations, find the value of 5x plus 5y.
00:05
In the system we're given is 2x plus 3y equals 6, and 8x plus 7y equals 4.
00:10
And we are going to attempt to solve this using one of our algebraic methods, and the method we'll use is elimination.
00:17
And what we need to do for elimination is to make some of our coefficients of the same variable match, but with alternating signs.
00:24
So we would like for this 2x to become a negative 8x, so we'll multiply the entire top equation by negative 4, which distributes negative 4 to both variables and the constant.
00:36
That gives us negative 8x minus 12y equal to negative 4 times 6, which is negative 24.
00:44
And now we should be able to eliminate x when we add vertically.
00:48
8x plus negative 8x eliminates the x's.
00:51
7y plus negative 12y, or 7y minus 12y is negative 5y, equal to 4 minus 24, which is negative 20...