Question 261619

3 hours 20 minutes. is not 3.2 but 3 1/3 or 10/3
10/3*x+10/3(x-15)=390
10/3(2x-15)=390
I get x=66
check
10/3*66+10/3(66-15)=390
220+10/3*(51)=390
220+170=390
ok
check
10/3(2*66-15)=390
10(2*22-5)=390
10*(44-5)=390
10*39=390
ok