The answer is c. 7•2= 14, then 7+7= 14+2= 16+2= 18
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
B. 2 time 2 is 4 , 4 times two is 8, 8 times five is 40
Answer:
55
Step-by-step explanation:
You need to find the GCF (greatest common factor) of 45 and 90, which is 45.
45 times ? gets you 45
? would be 1
45 times 1 equals 45.
45 times ? gets you 90
? would be 2
45 times 2 equals 90
45(1+2) = 45+90 = 135
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