Question 73402
Let c=price of chocolate bar, g=price of gum
The word problem translates to 
{{{3c+g=1.75}}}Sally bought three choclate bars and a pack of gum and paid $1.75
{{{2c+4g=2}}}Jake bought two choclate bars and  four packs of gum and paid $2.00
Solve for g on the first equation
{{{g=1.75-3c}}}Plug this into g of {{{2c+4*highlight(g)=2}}}
{{{2c+4*highlight(1.75-3c)=2}}}Now distribute the 4
{{{2c+7-12c=2}}}Subtract like terms
{{{-10c=2-7}}}Subtract 7 from both sides
{{{-10c=-5}}}Divide both sides by -10
{{{c=-5/-10}}}
{{{c=1/2}}}
So the chocolate bar costs $0.50. Use this to find the price of gum
{{{2(.5)+4g=2}}}
{{{1+4g=2}}}
{{{4g=1}}}
{{{g=1/4}}}
So the gum costs $0.25
Check:
{{{3c+g=1.75}}}
{{{3(0.5)+0.25=1.75}}}
{{{1.5+0.25=1.75}}}
{{{1.75=1.75}}}Works
{{{2c+4g=2}}}
{{{2(0.5)+4(0.25)=2}}}
{{{1+1=2}}}
{{{2=2}}}Works