1 x 10 - 15 / 4.2 x 10 - 7
Due to order of operations you have to do do the multiplication and division first, from left to right.
So start with 1.0 x 10. This = 10.
Then you have to skip over the subtraction for now. Multiply 15 by 4.2. This equals 63. Then multiply this by 10, so 630.
Then rewrite the equation. It's 10 - 630 - 7. Then just subtract. 10 - 630 = -620.
-620 - 7 = -627. (Two subtracts make an add)
-627 is your answer
