Question 1180169
Sam had 3/5 as many flags as Mateo.
let mateo have x flags
Sam has 3x/5  flags

 Mateo gave 3 flags to Sam so that they would each have the same amount. 

x-3 = 3x/5  +3

x-3x/5 =3+3

2x/5 = 6

2x =30
x=15
mateo has 15 flags