Am stunned on how you can't do 5th grade math and you appear in High School... But I'll help
According to PEMDAS (Parenthesis, Exponents, Multiplication/Division, and Addition/Subtraction) you wanna do 5-9+18 first. That gives you 14. After 14, you do 14/7 which gives you 2. And finally, you do 24 - 2 which gives you 22.