Guys i at school rn and need help please thank xoxo

Three times the sum of a number and seven is negative thirty-six. what is the number?

1: 4 if the wew 35 surfboards at the beach how many were short boards?

Avery’s piggy bank has 300 nickels, 450 pennies, and 150 dimes. she randomly picks three coins. each time she picks a coin, she makes a note of it and puts it back into the piggy bank before picking the next coin.