" the sum " means add
the sum of 8 and a number...
8 + n <== ur expression
When the transverse axis is horizontal, a hyperbola centered at (h,k) has formula (x-h)^2/a^2-(y-k)^2/b^2=1. Plug in h=2, k=1, the formula is (x-2)^2/a^2-(y-1)^2/b^2=1 for some a,b. If the transverse axis is vertical, the formula is (y-h)^2/a^2-(x-k)^2/b^2=1, and (y-2)^2/a^2-(x-1)^2/b^2=1 in our case.
He can use addition by adding 0.44 and 1.224 together to see how much Vitamin B-12 (so far he has 1.664 in all.) he has right now. then he needs to subtract that amount (1.664) of B-12 he has from the amount of vitamin B-12 (2.4) he needs. That'll be 0.736 of vitamin B-12 he needs to reach the amount of B-12 he needs.
