Answer:
241 t-shirt and 49 short
Explanation:
lets call shorts x and tshirts y
x+y=290 (first equation)
4x+2y=678 (second equation) { we multiply the price of short with the short so we can get the pieces sold and also with the t-shirt to get the pieces sold)
x=290-y
and substitute it with x in the second equation
4(290-y)+2y=678 then till u get to y=241 (the pieces sold)
290-241=49 (pieces sold)
so as proof 49+241=290 pieces sold
as proof also 4*49=196 price of all shorts sold
2*241=482 price of all t-shirts sold then add them together and u will get 196+482=678$