Let x be the money he needs
You have earned .7 of the money so .7x
Then you get 5 dollars
Now you have .7x+5
That equals 26.49
.7x+5 = 26.49
We have to solve this equation
.7x+5-5 = 26.49 -5
.7x = 21.49
Divide each side by .7
.7x/.7 = 21.49/.7
x = 30.7
The questions asks how much do you still need
Take the amount you need and subtract the amount you have
30.7 - 26.49
4.21
You still need to earn 4.21
.