Answer:
{x = -3
, y=2 (Isolved for both variables be elimination)
Step-by-step explanation:
Solve the following system:
{3 x + 5 y = 1 | (equation 1)
7 x + 4 y = -13 | (equation 2)
Swap equation 1 with equation 2:
{7 x + 4 y = -13 | (equation 1)
3 x + 5 y = 1 | (equation 2)
Subtract 3/7 × (equation 1) from equation 2:
{7 x + 4 y = -13 | (equation 1)
0 x+(23 y)/7 = 46/7 | (equation 2)
Multiply equation 2 by 7/23:
{7 x + 4 y = -13 | (equation 1)
0 x+y = 2 | (equation 2)
Subtract 4 × (equation 2) from equation 1:
{7 x+0 y = -21 | (equation 1)
0 x+y = 2 | (equation 2)
Divide equation 1 by 7:
{x+0 y = -3 | (equation 1)
0 x+y = 2 | (equation 2)
Collect results:
Answer: {x = -3
, y=2
Step-by-step explanation:
0.9(17) -2.7(3) =
15.3-8.1
=7.2
We know that 20% of the first type of juice is pure fruit juice and 45% of second type of juice is pure fruit juice.
Now we have to make 30 pints of a mixture that is 35% pure.
Let x be the number of pints of first type of juice and y be the number of pints of second type of juice.
So, 
(Equation 1)
Since, 20% of x + 45% of y = 35.3% of 30
(Equation 2)
Solving equations 1 and 2,
we get y=18 and x=12.
So, 12 pints of first type of juice and 18 pints of second type of juice are used.
Answer:
3x - (15 x 3) = 90
or
3x - 45 = 90
Explanation:
there are 3 boxes. We don't know how many are in them yet, so we write this as 3x. However, we know that we give away 15 to 3 different teachers. 15 x 3 = 45
Therefore the first part is 3x - 45
We also know that in the end we have 90 left.
So our final equation is:
3x - 45 = 90
Answer:
325 miles and 77 dollars
Step-by-step explanation:
First, create equations. Let x equal the miles driven. The first plan expression is 38 + 0.12x and the second plan expression is 51 + 0.08x. Setting these equal and solve for x: 38 + 0.12x = 51 + 0.08x -> 0.04x = 13 -> x = 325 miles.
The cost is found by substituting it into any of the expressions: 51 + 0.08(325) = 77 or 38 + 0.12(325) = 77
