Question 107541
This is a 2 linear equations in 2 variables problem.  Let p be the cost of a pen and m be the cost of a marker.


Eq 1) {{{10p+15m=26}}} and


Eq 2) {{{5p+10m=16}}}


Multiply Eq 2) by -3 and Eq 1) by 2


Eq 3)  {{{-15p-30m=-48}}}

Eq 4) {{{20p+30m=52}}}



Then add 3) to 4) term by term:


{{{5p=4}}}

{{{p=0.80}}}



And pens cost 80 cents.


To check the answer, plug the 80 cents into Eq 1 or 2 to determine that markers cost $1.20, then


{{{10*0.8+15*1.20=26}}}  Check.