Solve the formula for converting temperature from degrees celsius to degrees fahrenheit for c answer

[10 points, algebra 2-simplifying complex fractions]according to my answer key the restrictions are -1 and 4. but why not positive 1?

A33 gram sample of a substance that's used to detect explosives has a k-value of 0.1473. n = noekt no = initial mass (at time t = 0) n = mass at time t k = a positive constant that depends on the substance itself and on the units used to measure time t = time, in days

Erin bought christmas cards for $2 each to send to her family and friends. which variable is the dependent variable?