Answer:
40
Step-by-step explanation:
Let the number be y
-1/2 × y = -20
y = -20 ÷ -1/2
y = 20 × 2
y = 40
Answer: 45 and 25
Step-by-step explanation:
Given
Five years ago victor was twice as old as his daughter
Suppose the current age of victor and his daughter are x and y
For five years ago

In 10 years sum of their ages is 90

On solving (i) and (ii) we get

So, the current age of victor is 45 and his daughter is 25
Answer: r≤10.4
Step-by-step explanation:
Initial depth - 12.8 feet
Maximum depth reached - 49.2 feet
49.2-12.8= 36.4 feet (maximum descent that the scuba diver can make)
Rate = Distance ÷ time
Distance - 36.4 feet
Time - 3.5 minutes
r= 
r= 10.4
As r is the maxmimum rate found, r cannot be greater than 10.4, so r must be less than or equal to 10.4.
Therefore, r≤10.4
Answer:
b(10) = 76
Step-by-step explanation:
To find b(10) substitute n = 10 into the formula
b(10) = - 5 + 9(10 - 1) = - 5 + 9(9) = - 5 + 81 = 76