algebra
posted by beverly .
what is 7x9y=13 and 9x+7y=91
elimination method

let's eliminate the y's
1st times 7 > 49x 63y = 91
2nd times 9 > 81x + 63y = 819
add them:
130x = 910
x = 7
back into 2nd ...
9(7) + 7y = 91
7y = 28
y = 4
x=7 , y = 4