This is how I'd set it up:
405/20 = 243/x
this means the mpg (miles / gallons) for 1 situation is the same as the mpg for the other situation (because the rate is the same)
then just cross multiply and solve:
405x=243*20 or 405x=4860 or x = 12
he would need 12 gallons of gas for 243 miles
Answer:
<em> 1,407</em>
<em>x 14</em>
<em>_______</em>
<em> 5,628</em>
<em>+ 1,4070</em>
<em>______</em>
19,698
<em>The two partial products are 5,628 and 14,070</em>
If you could put more info ab this then i would understand what u want me to put