ALGEBRA word problem

Question

One man and 3 children weigh the same as 7 children. If each child weighs 25 ​kg, then how much does a man​ weigh?  

Answer 1

Let's let m stand for man and c stand for child.

One man (m) and (+) 3 children (3c) weigh the same as (=) 7 children (7c)

m + 3c = 7c

Now, we were told that each child weighs 25 kg, so we can substitute 25 in for c.

m + 3(25) = 7(25)

m + 75 = 175 --> now solve for m, subtract 75 from both sides.

m = 100

The man weighs 100kg.