Answer: (2,4) They bought 2 sodas and 4 coffees.
Step-by-step explanation:
A. c + s=6 Â where c is the number of coffee and s is the number of sodas
B. 1.50c + 1.20s =8.40
C. -1.50 (c   +  s) =6(-1.50)  we will multiply the first equation by -1.50 to eliminate the c
 New equation;  -1.50 - 1.50s = -9     -0.3s/-0.3=-0.6/-0.3  s=2 Â
              -150 +  1.20s = 8.40     Â
So we know they bought 2 sodas. Â so we will plot 2 into the equation.
1.50c  + 1.20(2)=8.40  c= 4 Â