the number is 10

let the number be x

so,

5x + 7 = 57

5x = 57 - 7

5x = 50

x = 50/5

x = 10

Step-by-step explanation:

Let the number be x.

=7+5x=57

=5x=57−7

=5x=50

=x=50/5

=10.