70 Years Old Algebra Equation Funny 70th Birthday Math Shirt Solid colors: 100% Cotton; Heather Grey: 90% Cotton, 10% Polyester; All Other Heathers: 50% Cotton, 50% Polyester Imported Machine wash cold with like colors, dry low heat Funny t-shirt for any 70 year old math nerd Great 70th birthday gift for anyone who enjoys a little math humor Lightweight, Classic fit, Double-needle sleeve and bottom hem