13. for what value of b would the following system of equations have an infinite number of solutions? 9x + 12y = 21
6x + 8y = 7b explain and show steps : )

b=2

Step-by-step explanation:

9x + 12y = 21

6x + 8y = 7b

To have an infinite number of solutions, the two equations must be equal

Take the first equation and divide by 3, since it is a factor of all the terms

9x/3 + 12y/3 = 21/3

3x+4y = 7

Then multiply by 2 to get the x term equal

2*3x + 2*4y = 2*7

6x +8y = 7*2

Comparing this to the second equation

6x + 8y = 7b

b must equal 2

c.   x=2.4cm

step-by-step explanation:

similar triangles are triangles which have the same shape but not the same size. this means their angle measures are equal but their side lengths are not instead they are proportional. to solve, we will set up a proportion and solve.

a proportion is two equal ratios set equal to each other. we form the ratios by finding corresponding sides (sides which match to each other on both triangles by their position). out ratios will be one side of the small triangle over the corresponding side on the big triangle as shown below:

.

to solve the proportion, we'll cross multiply by multiplying numerator with denominator across the equal sign.

the correct answer would be:

220 centimeters

to get this you can use the pythagorean theorem

hope this

step-by-step explanation: