Question 725032
ASSIGN VARIABLES
u= UNKNOWN, how many pounds of $6/pound coffee
v= 70, the number of pounds of $15/pound coffee
L= $6/pound
H= $15/pound
T= $12/pound WANTED


WRITE EQUATIONS FOR THE SITUATION
{{{highlight((uL+vH)/(u+v)=T)}}}
Solve for u, and then substitute known or given values to evaluate.


SOLVING FOR u
{{{uL+vH=T(u+v)}}}
{{{uL+vH=Tu+Tv}}}
{{{uL-Tu=-vH+Tv}}}
{{{u(L-T)=Tv-vH}}}
{{{u(L-T)=v(T-H)}}}, multiply both members by (-1) because of the order of L, T, and H
{{{u(T-L)=v(H-T)}}}
{{{highlight(u=v(H-T)/(T-L))}}}, the formula for u.


SUBSTITUTE VALUES
The final computation using the known or given values is left undone, for you to do.