Alright, lets get started.
The ages of all four sisters will be = x, x+2, x+4, x+6
As per given in question, two times of youngest sister age exceeds the oldest sister age by 30 means
Simplifying the equation
So this is the age of youngest sister.
So, age of oldest sister will be 
Hene the age of oldest sister is 42 years. : Answer
Hope it will help :)
W+d=869
w=d-81
plug in
(d-81)+d=869
2d-81=869
+81 both sides
2d=950
÷2 both sides
d=475
dryer cost $475
let's check w=475-81
w=394
475+394=869
869=869
the solution is true :)
This is a true statement.
Consider two events A and B. We say they are complementary if P(A)+P(B) = 1
This means that either event A or event B must happen, since the "1" represents 100% probability. Having a probability of 100% means absolute certainty.
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Example:
A = the event it rains
B = the event it does not rain
P(A) = 0.30 = 30% chance of rain
P(B) = 0.70 = 70% chance it does not rain
P(A)+P(B) = 0.30+0.70 = 1
So this shows the two events are complementary.
