I am pretty sure the answer is,
B
Hello!
This submarine rose 100 feet (+100) and then descended (-100). Usually in an equation this would cancel out and make 0. Therefore, our answer is 0.
I hope this helps!
Answer:
b=9,a=12
Step-by-step explanation:
I solved by substitution:
b = 3/4a ---> plug this into the other equation
a + b = 21 is now a + 3/4a = 21
Reduce: 7/4a = 21
a = 12
Now solve for b:
b=3/4a is now b=3/4(12)
b=9
