Question 579592
"The football team has 45 members" ___ j + s = 45


"There are twice as many juniors as seniors" ___ j = 2s


subtracting the 2nd equation from the 1st (to eliminate j) ___ j + s - j = 45 - 2s


s = 45 - 2s ___ 3s = 45


solve for s, then substitute back to find j