Problems Solve

 WALT: solve number problems
So Matthew has to sell 75 bars of chocolate enough money to pay for his school camp. He has sold 38 so far. How many more chocolate bars does he need to sell for school camp. So I think it 37 so How I number solve it was how 70-30=40 then he taken away the 8-5=3 then 3-40=37 then the answer is 37 then Matthew has 37 bucks.