Acondominium building has 25 condo units. each unit has 5 windows. ryder said that there are 125 windows altogether.

which estimate can be used to see if ryder’s answer is reasonable? is ryder correct?

a.
30 × 5
the answer is not reasonable. ryder is not correct.

b.
30 × 5
the answer is reasonable. ryder is correct.

c.
30 ÷ 5.
the answer is not reasonable. ryder is not correct.

d.
30 + 5.
the answer is reasonable. ryder is correct.