P6 Rate . P6 percentage

Hi Mr Chang, i have 2 questions which i cannot solve. Can you help me?

 

1) Henry can wash a car in 2 hours. Dolly can wash the same car in 3 hours. How long will it take Henry and Dolly to wash the same car together?

 

2) Jane and Iris has 255 sweets altogether. Jane had 15 more sweets than Iris. Jane gave away 25% as many sweets as Iris. She was left with twice as many sweets as Iris.

 

a) how many sweets did Iris give away?

b) how many sweets did Jane have in the end?

 

thanks,

Jayden