We can't eliminate as is so we have to change something up there in the equations to get either the x values the same number but opposite signs, or the y values the same number but opposite signs. I chose to change the y values to the same number but different signs. In the first equation y is -3y and in the second one, y is -8y. The LCM of both of those numbers is 24, so we will multiply the first equation by an 8 (8*3=24) and the second equation by 3 (3*8=24) but since they are both negative right now, one of those multiplications has to involve a negative because - * - = +. Set it up like this:
8(-10x - 3y = -18)
-3(-7x - 8y = 11)
Multiply both of those all the way through to get new equations:
-80x - 24y = -144
21x +24y = -33
Now the y's cancel each other out leaving only the x's:
-59x = -177 and x = 3. Now plug that 3 into either one of the original equations to find the y value. Either equation will work; you'll get the same answer using either one. Promise. -7(3) - 8y = 11 gives a y value of -4. so your solution is (3, -4) or B above.

7 0

3 years ago

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Which transformation will map an isosceles trapezoid onto itself? rotation by 180° about its center, reflection across a diagona

alukav5142 [94]

Answer:

The correct option is 4.

Step-by-step explanation:

The non parallel sides of an isosceles trapezoid are congruent.

The image of an isosceles trapezoid is same as the preimage of isosceles trapezoid if

1. Reflection across a line joining the midpoints of parallel sides.

2. Rotation by 360° about its center.

3. Rotation by 360° about origin.

If we rotate the trapezoid by 180° about its center, then the parallel sides will interchanged.

If we reflect the trapezoid across a diagonal, then the resultant figure will be a parallelogram.

If we reflect across a line joining the midpoints of the nonparallel sides, then the parallel sides will interchanged.

After rotation by 360° about the center, we always get an onto figure.

Therefore option 4 is correct.

6 0

2 years ago

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Your company recently made a purchase of 25 identical tables. The purchase price after adding 5 percent sales tax was 1,706.25.

ELEN [110]

If c = the cost of one table, the cost of all 25 tables before sales tax is 25·c

Since the sales tax is 5%, or 0.05, the sales tax for 25 tables is 25·c·0.05

Adding the sales tax to the original cost of the 25 tables can give you:
25·c + 25·c·0.05 = 1706.25
1.05·25·c = 1706.25
26.25·c = 1706.25
c = $\frac{1706.25}{26.25}$ = 65

so the refund for 5 tables would be 5*65 = $325

4 0

2 years ago