Kaylin mixed two liquids for a science experiment. One container held 7/8 cup and the other held 9/10 cup. What is the total amount of mixture?

Please help me, I can't seem to do it right!
Thank you! :)

Respuesta :

7/8 times 10= 70/80 

9/10 times 8= 72/80

(i did this so the bottom number would be the same)

70+72=142

142/80