Write the equation popcorn, x drinks, y 51.25 = 5x + 5y 122.25 = 15x + 8y
<span>Multiply the 1st row by 3 </span><span>15x+15y=153.75</span> <span><span><span>15x+8y=122.25</span>1 </span></span><span>Subtract the 2nd row from the 1st row </span>7y=31.<span>5 </span>Divide both sides by <span><span>7 </span></span>y=<span><span><span>31.5</span></span><span>/7 simplify y = 4.5
</span></span>Substitute <span>y=4.5</span><span> into any of the two equations above Let's pick the first equation </span><span><span><span>15x+15y=153.75 </span></span></span>15x+15(4.5)=153.75 <span>Simplify </span>15x+67.5=153.7<span>5 </span>Subtract <span>67.5</span> from both sides 15x=153.75−67.<span>5 </span><span>Simplify </span><span>15x=86.25</span> Divide both sides by <span><span><span>15 </span></span></span><span>x=<span><span><span>86.25</span></span><span>/15 Simplify </span></span></span><span><span>x=5.75
When one variable increases (the price) while the other variable decreases (the number of hamburgers he sells) , a negative linear relationship exists.
