7. Tessa bakes muffins in an oven. • The oven takes 10 minutes to warm up before the first tray of muffins can be baked.
• Each tray of muffins takes 20 minutes to bake.
How much time will have passed from when the oven starts warming up until Tessa finishes the third tray
of muffins?

A.30 mins
B.50 mins
C.60 mins
D70 mins