Work out the answers to:
a) 13+ (-20)
b) (-14) + (-11)
c) 18 -(-9)
d) (-21)-(-36)

a. -7

b. -25

c. 27

d. 15

Step-by-step explanation:

distance covered by pamela in 9 l of fuel = 99km

let us apply unitary method here.

distance covered by pamela in 1 l of fuel =99/9 =11 km

now let us find distance covered by pamela if she has 12 l of fuel.

distance covered in 12 l = distance covered in 1 l of fuel * 12

we know that distance covered by here in 1 l is 11 km.

so distance covered in 12 l of fuel = 11*12 = 132 km.