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:
z equals 13 yeeeeeeeeetttttttttttttt I hopppppeeeee thhhhhaaaaatttttt heeeeelllllllpppppppsssssss
<h3>x²+5x+3+2x²+10x15 =0</h3><h3>x²+2x²+5x+10x+3+15=0</h3><h3>3x²+15x+18=0</h3><h3>3(x²+5x+6) =0 because 3 is common factor</h3><h3>3(x²+3x+2x+6) spill the middle term</h3><h3>3(x(x+3)+2(x+3) take the common factor from term</h3><h3>3(x+2) (x+3)</h3>
<h3>answer is 3(x+2) (x+3)</h3>
please mark this answer as brainlist