Answer:
40 + 4x
Step-by-step explanation:
formula for perimeter:
( length * 2 )+(width * 2)
you know that the length and width will be increased by the same number so you can call that X.
((length + x)*2) + ((width + x) * 2)
then substitute length and width
((15+x)*2) + ((5+x)*2))
you can simplify this a bit more
30 + 2x + 10 + 2x
40 +4x
Goodluck with your schoolwork/homework!
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Sorry for any wrong answers or bad explanations.