F.1 maths(one que.)

e種問題會比埋有邊2種coins，如果唔係唔會有答案，我就當係$5 coins吧

let the number of $2 coins be y , then we have the number of $5 coins be 135-y

thus we have (135-y)(5)+(2)(y)=348
675-5y+2y=348
3y=327
y=109

thus the number of $2 coins is 109