Use two equations in two variables to solve the application.

Two pairs of shoes and four pairs of socks cost $109, and three pairs of shoes and five pairs of socks cost $160. Find the cost of a pair of socks.
$

The  of a pair of socks is $3.5

Step-by-step explanation:

Let

x ---> the cost of a pair of shoes

y ---> the cost of a pair of socks

we know that

----> equation A

---> equation B

Solve the system of equations by graphing

Remember that the solution of the system of equations is the intersection point both graph

using a graphing tool

The solution is the point (47.5,3.5)

see the attached figure

therefore

The  of a pair of socks is $3.5

answer: what are the following choices

explanation:

infrared radiation has wavelength in the range between 700 nm and 1 mm. lets' convert these values into scientific notation, keeping in mind that:

let's start from the lower value, we have:

(we moved the dot two places to the left, so we increased the exponent by 2 units, from -9 to -7)

the higher value is:

so, the range of wavelength of infrared radiation is: