Extrinisic motivation is about doing something for a reward or for a score! There are times when this is useful. However we really need to develop Intrinsic motivation!
The love of doing something because he or she knows it will benefit them, that they're not doing it for the tangible reward. The love of doing something because they enjoy it. Does your child enjoy reading? If they don't, do they have somewhere comfortable to sit (like a bean bag or a reading corner filled with cushions) and a range of reading material that interests them or are they having to read something they have no interest in? Do they see the fun and use in what they are having to learn? Is there real world application in what they are doing?
Give the math activities a go. Have them see that learning is fun and everyone gets involved! Play the car licence plate game when you're driving somewhere as a family. Model reading by also reading your own book or other material when they are reading.
I have attached more information with links to their website sources which help to explain the importance of developing Intrinsic motivation and a growth mindset.