Woolworths had a going out of business sale. The price of a telephone before the sale was $39.98. What was the price of the telephone after a 30% discount? If the sale price of the same telephone had been $23.99, what would the percentage discount have been?

Each person in an it department of 25 people works on at least one of 3 major projects: system security, program implementation, platform development. 10 people work on system security, 13 work on program implementation, and 12 work on platform development. 4 people work on system security and platform development, 5 people work on program implementation and platform development, and 2 people work on all three projects. how many people work on system security and program implementation?