Answer: 35
the age of Roberto is x (x > 3)(x ∈ N)
because Roberto is 3 years older than Carolyn => the age of Carolyn is x - 3
in 7 years, the age of Roberto is x + 7; the age of Carolyn is x - 3 + 7 = x + 4
because In 7 years the sum of their ages will be 81 =>
x + 7 + x + 4 = 81
⇔ 2x + 11 = 81
⇔ 2x = 70
⇔ x = 70/2 = 35
=> the age of Roberto is 35
Step-by-step explanation:
Answer: She bought 28 daises and 10 Tulips.
Step-by-step explanation:
Let x represent the number of daises bought.
Let y represent the number of tulips bought.
Your friend want to have 38 of her favorite flowers. This means that
x + y = 38
Her favorite flowers are daisies at 1.50 each and tulips at 2.50 each if the total bill was 67, it means that
1.5x + 2.5y = 67 - - - - - - - - - - - - 1
Substituting x = 38 - y into equation 1, it becomes
1.5(38 - y) + 2.5y = 67
57 - 1.5y + 2.5y = 67
- 1.5y + 2.5y = 67 - 57
y = 10
x = 38 - y = 38 - 10
x = 28
The third option since they both will cross at 5-10 on the graph
The Answer Is Nine, Because :
A Coefficient Is <span>A number used to change a variable.</span>
<span><span>let x = cows last year
</span>
</span><span><span>let y = bulls last year
</span>
</span><span><span>x + y = last years total
</span>
</span><span><span>0.9x + 1.5y = 660 (this year's total)
</span>
<span>1.1(x+y) = 660 </span>= </span><span>1.1x + 1.1y = 660
</span><span>
</span><span><span>so:
</span>
</span><span><span>0.9x + 1.5y = 1.1x + 1.1y
</span>
</span><span><span>subtract 0.9x from each side:
</span>
</span><span><span>1.5y = 0.2x + 1.1y
</span>
</span><span><span>subtract 1.1y from each side
</span>
</span><span><span>0.4y = 0.2x
</span>
</span><span><span>to make x 1 multiply both sides by 5
</span>
</span><span><span>2y = x
</span>
</span><span><span>substitute for x in one of the original problems:
</span>
since they had 660 this year and that number is 10%
higher than last year, then we had 600 total last year. </span>
<span><span>So:
</span>
</span><span><span>600 = x + y
</span>
</span><span><span>substitute into that one with the 2y = x
</span>
</span><span><span>600 = 2y + y
</span>
</span><span><span>600 = 3y
</span>
</span><span><span>200 = y
</span>
</span><span><span>then 600 - y = x
</span>
</span><span><span>so 600 - 200 = x
</span>
400 = x</span>
<span> So you had 400 cows and 200 bulls last year</span>
