How did the Allies fight back against U-Boats? a. They built their own submarines that could trace and destroy the U-boats underwater.

b. They used spies embedded in the German Navy to find out where the U-boats were going to be.

c. They stopped using ships and started using airplanes to attack U-boats from the sky.

d. They developed new technologies and tactics that could destroy U-boats.

simplify brackets

8 - 2a - 7 = a + 40

simplify 8 - 2a - 7 to -2a + 1

-2a + 1 = a + 40

add 2a to both sides

1 = a + 40 + 2a

simplify a + 40 + 2a to 3a + 40

1 = 3a + 40

subtract 40 from both sides

1 - 40 = 3a

simplify 1 - 40 o -39

-39 = 3a

divide both sides by 3

-39/3 = a

simplify 39/3 to 13

-13 = a

switch sides

a = -13

hi, according to my research the answer to the first question would be false. al tabari was the author of the first medical encyclopedia & he was a persian scholar not arab