Max can mow a lawn in 45 minutes. jan takes twice as long to mow the same lawn. if they work together, how long will it take them to mow the lawn?

We can solve this by expresing their work in rate as how fast they are doing.
Max mows at speed of 1/45
Jan takes 1/90

When we sum those 2 rates we calculate how much will need for them to mow the lawn or in other words their sum to equal 1

1/45x + 1/90 x= 1
3/90x = 1
1/30x = 1
x = 30

Answer is 30