
Thomas N. answered 04/01/20
MIT Mechanical Engineer for Math and Science Tutoring
To solve his problem you need to set up 2 equations with 2 unknowns. The two unknowns are:
a = # of first class tickets
b = # of coach tickets
the first equation is that the number of first class tickets + coach tickets must add up to 14 total tickets:
EQ1: a+b = 14
the second equation is trickier but is the (number of first class tickets)*(price of a first class ticket) + (number of coach tickets)*(price of a coach ticket) = $9770:
EQ2: a*($980) + b*($190) = $9770
the rest of the problem can be solved many ways but one way is:
rearrange EQ1: b = 14 - a
plug in the rearranged equation in EQ2
a*($980)+ (14-a)*($190) = $9770
a*980-a*($190) + 2660 = $9770
solve for a:
a = 9
so 9 first class tickets were purchased