Average force question?

When a 81.3 - g slice of bread is inserted into a toaster, the toaster's ejection spring is compressed by 7.05 cm. When the toaster ejects the toasted slice, the slice reaches a height 3.4 cm above its starting position. What is the average force that the ejection spring exerts on the toast? What is the time over which the ejection spring pushes on the toast? Assume that thoughout the ejection process, the toast experiences a constant acceleration.