4 I think i'm sorry if I get it wrong. Hope I helped ≥ω≤
Answer:
<em>Cathy was born in 1980 and she was 18 years old in 1998</em>
Step-by-step explanation:
<u>Equations</u>
This is a special type of equations where all the unknowns must be integers and limited to a range [0,9] because they are the digits of a number.
Let's say Cathy was born in the year x formed by the ordered digits abcd. A number expressed by its digits can be calculated as

In 1998, Cathy's age was

And it must be equal to the sum of the four digits

Rearranging

We are sure a=1, b=9 because Cathy's age is limited to having been born in the same century and millennium. Thus

Operating

If now we try some values for c we notice there is only one possible valid combination, since c and d must be integers in the range [0,9]
c=8, d=0
Thus, Cathy was born in 1980 and she was 18 years old in 1998. Note that 1+9+8+0=18
Answer: 16 units
Step-by-step explanation:
Find the length of each of the four sides and add them all together. The short sides each measure 3 units and the long sides each measure 5 units. 3+3+ 5+5 = 16
$9.47
I just multiplied the total by the refund percentage to get that number. It’s just like finding a tip.
Answer:
The answer is 33 years.
Step-by-step explanation:
10% of 3 is .3
Just move the decimal to the left.
.3 times 33=9.9
9.9~10