If a fourth plant produces 150 widgets in 60
days, which statement is true?

the complete question in the attached figure

the statements are

1) It makes less than plant B

2) It makes the same as plant A

3) It makes more than plant C

we know that

analyzing the graph

plant A

for x=40  y=100

for x=50   y=200

that means 

the production in 10 days is 100 widgets

then

the production in 60 days will be 6*100> 600 widgets

so

plant A production  > plant fourth production

plant fourth production < plant A production

plant B

for x=40  y=0

for x=60   y=100

that means 

the production in 20 days is 100 widgets

then

the production in 60 days will be 3*100> 300 widgets

so

plant B production  < plant fourth production

plant fourth production > plant B production

plant C

for x=20  y=0

for x=40   y=100

that means 

the production in 20 days is 100 widgets

then

the production in 60 days will be 3*100> 300 widgets

plant C production  < plant fourth production

or 

plant fourth production > plant C production

if a = 1,   and b = 2, then the answer is 47.99999999. if you round that to the nearest whole number, the answer is 48.