Middle school math word problem... please help me

Question

If Machine A makes a yo-yo every five minutes and Machine B takes ten minutes to make a yo-yo, how many hours would it take them working together to make 20yo−yos?

Answer 1

A makes 12 every hour

B makes 6 every hour

 

h represents the number of hours

 

12h + 6h = 20

18h = 20

 

Can you solve for h and answer?