10. 4,200 cm
This is the correct answer!
I feel sorry for Becky and Tommy. The one who didn't come up with x=-10/3 made an error.
first bring 8x to the left and -25 to the right and simplify:
-4x-8x = 25+15 => -12x = 40
x = -40/12 = -10/3
Slimination
multiply first equaiton by 2
2x+6y=10
add to second equiaotn
2x-2x+6y-6y=10-10
0=0
this is true so therfor they are the same equaiton
so solve
x+3y=5
3y=-x+5
y=-1/3x+5/3
subsituter values for x and get valuse for y
if x=2 then y=1
You can start by doing 3×3 which is 9 than get the 9 and multiply it by 11 which would be 99