His hourly rate is $13.75.
Let x be the hourly rate. Since he works 20 hours that week, the hourly wages are given by 20x. We add to that his commission, which is 16% of the $1500 in sales, or 0.16(1500). This totals to 515:
20x + 0.16(1500) = 515
20x + 240 = 515
Subtract 240 from both sides:
20x + 240 - 240 = 515 - 240
20x = 275
Divide both sides by 20:
20x/20 = 275/20
x = 13.75.
4-7x= 39
Subtract 4 from both sides
-7x= 35
Divide both sides by -7
x= -5
The value of x+1= (-5)+1= -4.