Respuesta :

Suppose you receive x tokens, the total number of token is 20+x, at 1.40 dollar each. The total cost for the 20+x token at $1.40 each is the same as 20 tokens at $1.75 each. so we have the equation
1.40*(20+x)=1.75*20
28+1.40x=35
1.4x=7
x=5