Answer:
delivering 180/45 = 4 hours and return trip 180/60 = 3 hours
Step-by-step explanation:
d = unknown number to calculate each trip
[tex]\frac{d}{45}[/tex] + [tex]\frac{d}{60}[/tex] = 7
find common denominator (45 * 60 = 2700)
([tex]\frac{60}{60}[/tex])*([tex]\frac{d}{45}[/tex]) +( [tex]\frac{45}{45}[/tex])*([tex]\frac{d}{60}[/tex]) =7
[tex]\frac{60d}{2700}[/tex] + [tex]\frac{45d}{2700}[/tex] =7
[tex]\frac{60d + 45d}{2700}[/tex] =7
[tex]\frac{105d}{2700}[/tex] = 7
105d = 7 * 2700
105d = 18,900
d = 18900/105
d = 180
delivering 180/45 = 4 hours
return trip 180/60 = 3 hours
