x/y = 7/3
(x+15)/(y-8) = 5/2
即
x = 7y/3
5y-2x = 70
解方程组得
x= 490
y = 210
所以原来甲乙分别有490张和210张邮票不懂。说清楚点。假设原来甲乙分别有x张和y张邮票，根据题意有方程组x/y = 7/3(x+15)/(y-8) = 5/2方程组变换一下，成为x = 7y/3(1)5y-2x = 70(2)把（1）式代入（2）式得y = 210再根据（1）式得x = 490