Answer:
Speed of car B is 33 km/h and speed of car A is [tex]45\,\,km/h[/tex]
Step-by-step explanation:
Let speed of car B be [tex]x[/tex] km/h
Speed of car A is 12 km/h more than car B.
Therefore,
Speed of car A = [tex](12+x)[/tex] km/h
Distance = Speed × Time
Distance travelled by car A in 4 hours = [tex]4(12+x)[/tex] km = [tex](48+4x)[/tex] km
Distance travelled by car B in 4 hours = [tex]4x[/tex] km
Also, cars A and B are 312km apart after 4 hours.
[tex]48+4x+4x=312\\48+8x=312\\8x=264\\\\x=\frac{264}{8}\\\\x=33\,\,km/h[/tex]
Speed of car B is 33 km/h and speed of car A is [tex]12+x=12+33=45\,\,km/h[/tex]
