Photons of red light have a wavelength of approximately meters. The energy of a photon is inversely proportional to its wavelengt

Photons of red light have a wavelength of approximately $$$7\times 10^{-7}$$$ meters. The energy of a photon is inversely proportional to its wavelength. A photon with 2000 times the energy as a photon of red light will have a wavelength that can be written as $$$a\cdot 10^b$$$ meters, where $$$1\le a < 10$$$. (In other words, in scientific notation.) What is a + b written as a decimal?