Steps:
Boys: 30+40+50+60+60+70+70+70+80+80+80+90+90+100 = 970
Girls: 10+20+50+50+60+70+70+80+80+80+90+100 = 760
THEN Divide the sum of boys and girls but how many numbers you added
970 ÷ 14 = 69.2
910 ÷ 12 = 63.3
