. Ann can ice a cupcake in 30 seconds. Sarah can ice a cupcake in 40 seconds. Working Together, how many seconds will it take them to ice all 35 cupcakes?

600seconds

Step-by-step explanation:

If Ann can ice a cupcake in 30 seconds, then the total number of cupcakes iced by ann is t/30 cupcakes

Similarly, If Sarah can ice a cupcake in 40 seconds, then the total number of cupcakes iced by Sarah is t/40 cupcakes,

For them to ice 35cupcakes together, then;

t/30 +  t/40 = 35

where t is the times taken by both of them to ice 35cupcakes

Find the LCM

40t+30t/1200 = 35

70t/1200 = 35

7t/120 = 35

t/120 = 5

t = 120 * 5

t = 600

This shows that it will take them both 600seconds to ice 35cupcakes