Bridges on highways have expansion joints, which are small gaps in the roadway between one bridge section and the next. the gaps are put there so the bridge will have room to expand when the weather gets hot. suppose a bridge has gap of 1.4 cm when the temperature is 30c, and that the gap narrows to 0.9 cm when the temperature warms to 40c.
find the rate of expansion from 20c to 30c do not round

0.5 cm per 10 degrees

0.05 cm per one degree.

Step-by-step explanation:

For 30 degrees the bridge has a gap of 1.4 cm

For 40 degrees the bridge has a gap of 0.9 cm

The bridge expanded

1.4 cm - 0.9  cm = 0.5 cm per 10 degrees

Or, likewise

0.5/10 = 0.05 cm per one degree.

This means that for each degree that the temperature increases, the bridge will expand 0.05 cm

3

step-by-step explanation:

in standard form:

a= dictionaries

b= maps

you have to buy 3 dictionaries, so put a 3 next to the a (dictionaries) so that you can multiply them by each other.

a3+b= 60 (the amount of money you have)

we already know the cost of a=15 so replace a with $15

($15 x 3)+b=60

multiply 15 and 3 to get $45 and replace it with $45

45+b=60

and then replace b with 15 to get the total:

45+15=60

that means you have $15 left after buying 3 dictionaries.

15 divided by the cost of a map ($5) equals 3.

so you can buy 3 maps.

sorry if it was confusing!

i think the correct option is the second option.