Answer:
10
Step-by-step explanation:
"three times r" = 3r
"three times r minus ten" = 3r - 10
"product of 5 and the difference of three times r minus ten"
= 5 (3r - 10)
given that r = 4,
the expression becomes
5 (3r - 10)
= 5 [3(4) - 10]
= 5 [12 - 10]
= 5 (2)
= 10
Answer:
20 mph
Step-by-step explanation:
Let speed of Train a = Va mph
Let speed of Train b = Vb mph
Va = Vb + 30
Let time taken for Train a = Ta
Let time taken for Train b = Tb
time taken = distance travelled/speed
Ta = 350/Va = 350/(Vb+30)
Tb = 140/Vb
But they both travel in the same amount of time.
So, Ta = Tb

Cross multiply

Divide both sides by 210

2y = 5 hope this helps :)