At a game stall, each child needed 3 coupons to redeem a gift, while an adult needed 7 coupons. Given that 2/3 of the people who redeemed gifts with their coupons were children and total of 1248 coupons were collected by the gam stall, how many adults redeemed their gifts?
so, if there were x adults and 2x children, we have
7x + 3*2x = 1248
now finish it off