I would try drawing the line on a coordinate plane to help.
Total purchase she did : $20.90+$18.95=$39.85
7% tax means that we have to 7% or (7/100) extra
7% X 39.85= 2.79
total pay: 39.85+2.79=42.64
total cash: $50
what she gets back: 50-42.64=7.36
Answer:
35
Step-by-step explanation:
We know the factors of Lena's age are 2 and 5. The least common multiple must have these factors and the factors of 14, so will at least have factors of 2, 5, and 7.
Apparently, the dad's age is 5·7 = 35.
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The GCF is 5; the LCM is 70 = 5×14.
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Sometimes, I use a little 3-part diagram to think about LCM and GCF. Here, it would look like ...
(2 [5) 7]
where the numbers in curved brackets (2·5) and the numbers in square brackets [5·7] are factors of the two numbers of concern (Lena's age, her dad's age). The middle number in both brackets [5) is the greatest common factor, and the product of all three numbers is their least common multiple.
Here, the product of outside numbers, 2·7 = 14, represents the ratio of the LCM to the GCF. We know that Lena's age has factors of only 2 and 5, so the numbers in the diagram have to be (2[5)7], where 2 and 7 are on the ends and 5 is in the middle.
Let x be the value of the third term.
Since it's a geometric sequence, then:
Third term/Second term = Fourth term/Third term
x/20 = 11.25/x
Cross multiplication:
x^2 = 225
x = 15
So since the ratio is constant, then it is
x/20 = 15/20 = 3/4
So the common ratio is 3/4 or 0.75.
