Question 752968
since y = -3x, we can replace the 'y' in the first equation with '-3x'


so we go from


5x+4<font color="red">y</font>=7


to


5x + 4(<font color="red">-3x</font>) = 7


then multiply to get


5x - 12x = 7


Keep going to solve for x. Once you've found x, plug it into y = -3x to find y.