Randy had a lot of homework tonight. He needs to work for 45 minutes on social studies 40 minutes on science and 1 hour and 15 minutes on math. It will also take him 10 minutes to get ready for bed. If he wants to be in bed at 10:00on what time does he need to start his homework?

Answer: He needs to start his homework at 7:10.

Step-by-step explanation:

Hi, to answer this question we have to add all the times:

45 min (social studies)

40 minutes (science)

75 minutes (math) (1 hour and 15 minutes = 75 minutes)

10 minutes (to get ready)

Mathematically speaking:

45+40+75+10 = 170 minutes

If 60 minutes equals to 1 hour:

170/60 = 2.83 =

The hour is the integer part (2 hours)

The minutes is the decimal part multiplied by 60

0.83 x 60 = 50 minutes

So, 2 hours and 50 minutes, before 10:00.

10:00 - 2:50 = 7:10