13: on the first day of winter in the northern hemisphere, the sun is shining directly overhead in the noon time sky over what latitude? what else happens on the first day of winter in the northern hemisphere?

hello from mrbilldoesmath!

answer:

104 f = 40 c

discussion:

9/5c + 32 = f               => in our case, f = 104

9/5c + 32 = 104           => subtract 32 from both sides

9/5c         = 104 - 32   =>

9/5c   = 72                   => multiply both sides by 5/9 (the reciprocal of 9/5)

(5/9)*(9/5) c = 72 * (5/9) =>

c = 72*5/9 = 360/9 = 40

you,

mrb