Use PEMDAS (order of opperations)
P - parenthesis
E - Exbonents
M - Multiply
D - divide
A -add
S - subtract
You go in order except for the divison and multiplication you go from Left to right
Ex) 45/15(5x2)
Since thats in parenthsis yoh multiply it =10 the. Divide 45/15= 3 then multiply 10x3=30
