Equation - System Of Equation

SOURCE:COMPETITION
Number of Problems: 10. : (Book)

Let $a + 1 = b + 2 = c + 3 = d + 4 = a + b + c + d + 5$ . What is $a + b + c + d$ ?

$ext{(A)} -5 qquad ext{(B)} -10/3 qquad ext{(C)} -7/3 qquad ext{(D)} 5/3 qquad ext{(E)} 5$

The sum of three numbers is $20$ . The first is four times the sum of the other two. The second is seven times the third. What is the product of all three?

$mathrm{(A) } 28qquad mathrm{(B) } 40qquad mathrm{(C) } 100qquad mathrm{(D) } 400qquad mathrm{(E) } 800$

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The sum of three numbers is $20$ . The first is four times the sum of the other two. The second is seven times the third. What is the product of all three?

$mathrm{(A) } 28qquad mathrm{(B) } 40qquad mathrm{(C) } 100qquad mathrm{(D) } 400qquad mathrm{(E) } 800$

A school store sells 7 pencils and 8 notebooks for $mathdollar 4.15$ . It also sells 5 pencils and 3 notebooks for $mathdollar 1.77$ . How much do 16 pencils and 10 notebooks cost?

$ext{(A)}mathdollar 1.76 qquad ext{(B)}mathdollar 5.84 qquad ext{(C)}mathdollar 6.00 qquad ext{(D)}mathdollar 6...$

Suppose that $frac{2}{3}$ of $10$ bananas are worth as much as $8$ oranges. How many oranges are worth as much as $frac{1}{2}$ of $5$ bananas?

$mathrm{(A)} 2qquadmathrm{(B)} frac{5}{2}qquadmathrm{(C)} 3qquadmathrm{(D)} frac{7}{2}qquadmathrm{(E)} 4$

The product of two positive numbers is 9. The reciprocal of one of these numbers is 4 times the reciprocal of the other number. What is the sum of the two numbers?

$extbf{(A)} frac{10}{3}qquad extbf{(B)} frac{20}{3}qquad extbf{(C)} 7qquad extbf{(D)} frac{15}{2}qquad extbf{...$

The sums of three whole numbers taken in pairs are 12, 17, and 19. What is the middle number?

$extbf{(A)} 4qquad extbf{(B)} 5qquad extbf{(C)} 6qquad extbf{(D)} 7qquad extbf{(E)} 8$

10.