Question 57161
A single dose of a dietary supplement contains 0.2 gram of calciun and 0.2 gram of vitamin C. A single dose of a second dietary supplement contains 0.1 gram of calcium and 0.4 gram of vitamin C. If a person wants to take 0.6 gram of calicum amd 1.2 grams of vitamin C, how many doses of each supplement should she take?
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Let "a" be the number of 1st dietary supplement and "b" be the number of 
2nd dietary supplement:
EQUATIONS:
calcium: a(0.2)+b(0.1)= 0.6
Vit C  : a(0.2)+b(0.6)=1.2
Subtract "calcium" from Vit C to get:
0.5b=0.6
b=1.2
Substitute into "calcium" to get:
a(0.2)+(1.2)(0.1)=0.6
0.2a +(0.12) =0.6
0.2a=0.48
a=2.4
Chec the answer in Vit C.
It checks.

She needs 2.5 does of 1st dietary supplement and 1.2 does
of 2nd dietary supplement.
Cheers,
Stan H.