The average temperature for Monday, Tuesday, Wednesday and Thursday was 48 degrees and for Tuesday, Wednesday, Thursday and Friday was 40 degrees. If the temperature on Monday was 42 degrees. Find the temperature on Friday?  Pick.
A) 8	B) 9	C) 10	D) 12	E) 16

Rationale: "m + tu + w + th = 4 * 48 = 192 tu + w + th + f = 4 * 40 = 160 m = 42 tu + w + th = 192 - 42 = 150 f = 160 – 150 = 10 answer : c"
Answer: C